If Q(0, 1) is equidistant from P(5, –3) and R(x, 6), find the values of x. Also find the distances QR and PR.
PR = QR
\(\sqrt{(5-0)^2+(-3-1)^2}=\sqrt{(0-x)^2+(1-6)^2}\)
\(\sqrt{(5)^2+(-4)^2}=\sqrt{(-x)^2+(-5)^2}\)
\(\sqrt{25+16}=\sqrt{x^2+25}\)
41=\(x^2+25\)
\(x^2=16\)
\(x=\pm 4\)
Therefore, point R is (4,6) or (-4,6)
When point R is (4,6)
PR= \(\sqrt{(5-4)^2+(-3-6)^2}=\sqrt{(1)^2+(-9)^2}=\sqrt{1+81}=\sqrt{82}\)
QR= \(\sqrt{(0-4))^2+(1-6)^2}=\sqrt{(4)^2+(-5)^2}=\sqrt{16+25}=\sqrt{41}\)
When point R is (-4,6)
PR= \(\sqrt{(5-(-4))^2+(-3-6)^2}=\sqrt{(9)^2+(-9)^2}=\sqrt{81+81}=\sqrt{162}\)
QR= \(\sqrt{(0-(-4))^2+(1-6)^2}=\sqrt{(4)^2+(-5)^2}=\sqrt{16+25}=\sqrt{41}\)
Determine if the points (1, 5), (2, 3) and (– 2, – 11) are collinear
In a classroom, 4 friends are seated at points A, B, C and D. Champa and Chameli walk into the class and after observing for a few minutes Champa asks Chameli, “Don’t you think ABCD is a square?” Chameli disagrees. Using the distance formula, find which of them is correct.
| Case No. | Lens | Focal Length | Object Distance |
|---|---|---|---|
| 1 | \(A\) | 50 cm | 25 cm |
| 2 | B | 20 cm | 60 cm |
| 3 | C | 15 cm | 30 cm |